1. Field of the Invention
The present invention relates to a bending portion for endoscope configured to perform bending action according to operation of an operation member provided on an operation portion and to an endoscope including the bending portion for endoscope.
2. Description of the Related Art
In recent years, a medical device, such as an endoscope, inserted into a subject has been widely used in a medical field and an industrial field.
Particularly, in the endoscope used in the medical field, an elongated insertion portion is inserted into a body cavity that is a subject. An organ in the body cavity can be observed, and various treatments can be performed by using a treatment instrument inserted into an insertion channel of a treatment instrument included in the endoscope as necessary.
In a well-known configuration of the insertion portion of the endoscope, a bendable bending portion is provided to improve a property of insertion into the subject. A bending tube including a plurality of pivotably coupled bending pieces is included inside of a conventional bending portion, and the bending portion is bent by remotely operating turns of the plurality of bending pieces.
By the way, in an endoscope inserted into branched and complicated bronchi or the like, it is preferable that a distal end region of a bending portion is curved first to easily determine an insertion direction of an insertion portion in order to easily insert the insertion portion into a deep part of the bronchi.
Therefore, for example, International Publication No. 2013-190910 discloses an endoscope in which a bending tube formed by a hyperelastic tube body is provided in a bending portion to allow the bending portion to curve first.
International Publication No. 2013-190910 discloses a technique of the endoscope including: a plurality of slits formed on the bending tube; and a wire guide provided on an inner circumference of the bending tube, wherein slit intervals in a center region are formed longer than slit intervals of a distal end side region to allow the bending portion to curve first.